Hierarchical Decomposition and Interconnection Method for Efficient Thermal Simulation of Chiplet-Based 2.5D System

Thermal simulation is a key step in validating the performance of chiplet-based 2.5D systems. However, when dealing with the temperature-dependent parameters, the global nonlinear iteration may result in heavy computational cost. In this paper, an efficient hierarchical decomposition and interconnection (HDI) method is proposed for efficient thermal simulation of chiplet-based 2.5D systems. Firstly, the HDI method resolves the 2.5D system into two parts: the linear region and the nonlinear region. In the transient simulation, the response of the linear region is divided into a zero-input (ZI) one and a zero-state (ZS) one. In order to characterize the linear time-invariant properties of the ZS response, the impact of the linear region is further decomposed into the contributions of the face elements at the interface. In this way, an equivalent thermal boundary condition in the form of the thermal resistance matrix is established to represent the linear region. Then, we combine it with the nonlinear region to calculate the complete response in the interconnection process. By this means, the tedious iteration is confined to the nonlinear region, thereby reducing the computational complexity and improving the efficiency. To validate the accuracy and efficiency of the proposed HDI method, thermal simulation of a typical chiplet-based 2.5D system is performed, and a speed-up of 48× is achieved compared to the conventional finite volume method.